Party-line ringing device for telephone-switchboard circuits.



No. 767,573. PATENTED AUG. 16, 1904. J. W. LATTIG & G. L. GOODRUM. PARTYLINE RINGING DEVICE FOR TELEPHONE SWITGHBO'ARD GIRGUITS.

APPLICATION FILED JUNE 6, 1903. N0 MODEL.

N a L vn Zfiwsses.

UNITED STATES Patented August 16, 1904.

PATENT OFFICE.

JACOB W. LATTIG, OF WEST BETHLEHEM, AND CHARLES LANE GOODRUM,

. OF PHILADELPHIA, PENNSYLVANIA, ASSIGNORS TO EASTERN TELE- PHONEMANUFACTURING COMPANY, OF VIIESTCHESTER, PENNSYLVA- NIA, A CORPORATIONOF PENNSYLVANIA.

PARTY-LINE RINGING DEVICE FOR TELEPHONE-SWITCHBOARD CIRCUITS.

SPECIFICATION forming part of Letters Patent No. 767,573, dated August16, 1904. Application filed June 6, 1903. Serial No. 160,325. (Nomodel.)

'To all whom, it may concern.-

Be it known that we, JAooB LATTIG, residing in West Bethlehem, Lehighcounty, and CHARLEs LANE GrooDRUM, residing in Philadelphia, county ofPhiladelphia, Pennsylvania, citizens of the United States, have jointlyinvented a new and useful Party-Line Ringing Device forTelephone-Switchboard Circuits, of which the following is aspecification. I

Our invention relates to party-line ringingkey apparatus and circuits,having particular reference to those systems in which the subscribersringers are connected to the two limbs of the line, so that by sendingringing current of proper polarity over one limb or the other or bothsimultaneously any one bell or ringer may beactuated to the exclusion ofothers. Such-systems are currently denominated two-party selective,fourparty selective, and so on, according to the number of stations on aline. The simplest example of a selective party-line of this type is oneto which two stations are connected, each of which has its bell orringer normally included from one limb'of the line to ground, so that byputting a grounded generator to one side of line at central it will callone station and by putting it to the other side of line it will call theother station, using ordinary alternating current. By employingpulsating currents four substations may be connected in the same way,two stations having their ringers connected to one side of the line andtwo to the other, so that positive or negative pulsating current thrownon either side will actuate the ringer on that side only which is biasedto respond thereto. In systems of this kind it is customary to employ atthe 4 central oflice a selective ringing-key having a movable part orparts adapted to be set by the operator to the number or letter of thestation to be called, the generator being then automatically connectedin proper relation with the cord-conductors without further thought onthe part of the operator.

Some

times this selective key connects the generator directly to the circuitsand sometimes in proper relation to the contacts of an ordinaryringing-key. The latter is the best practice, 5 for if the selective keybe arranged to normally connect the generator in given relation suchstations as can thereby be called require only the use of the ordinaryringing-key, and the selective key need only be moved for a fractionalnumber of calls. With such an arrangement, however,- a difficulty oftenarises in that the selective key may be moved while a ringing-key isdownas, for instance, to make another callthereby causing confu- 6Osion, and in case the selective key is constructed to remain set afailure to restore it to normal position may cause confusion insubsequent calls.

It is the object of our invention to meet the 5 above objections andwhile retaining the convenience of the double-key arrangement to renderit impossible for any confusion to arise in the joint or separate use ofthe keys.

We attain our object by making the selec- 7 tive key automatic in itsreturn to one given position, but permitting its movement either to orfrom such position only when the ordinary ringing key or keys are in aninoperative position. In other Words, we look our selective key inwhatever position it may occupy when a ringing-key is down.

In arranging our apparatus on a switchboard each cord circuit is .fittedwith the ordinary ringing-key, which for convenience 30 we willhereinafter designate by the term ringing-key. In addition to these eachoperator is provided with a selective key connected to the ringing-keys,and this we shall hereinafter denominate the master-key, be- 5 causeprimarily it controls the disposition of the ringing-circuits. Obviouslythere may be several of these master-keys for each operator, if desired;but as this would involve mere multiplication of parts our description 9will be limited to one. If there are several, each would be appropriatedto its own group of cords by preference. Each master-key is providedwith a lock, and before it can'be set or unset it must be unlocked byhaving the cords clear or, in other words, all ringingkeys thrown up.

Our invention is fully described hereinafter and is illustrated in theaccompanying drawing, wherein the same letters and figures of referencepoint out the same parts throughout.

In the drawings, Figure l is a diagram of a system embodying ourinvention, showing central-oifice cord-circuits and line-terminals, withtwo lines leading to substations. Fig. 2 is a similar diagram of acord-circuit embodying the preferred form of our apparatus andconnections.

Referring to Fig. 1, 1 2 and 3 4 are two subscribers lines entering acentral station and there provided with suitable terminal jacks J and J.Each line is also provided with a line-relay L, controlling the localcircuit of a lamp-signal 1, and its two limbs pass throughimpedance-coils I and I to the busbars 5 and 6 of a main battery M. Theline 1 2 is shown passing to a single substation A, having the usualapparatus comprising transmitter T, receiver R, ringer Q, condenser C,and switch-hook H.

The line 3 4 is shown passing to two substations B and X. Each of thesehas the same apparatus as station A, and it will be noticed that theringer at station B is to ground from the line-wire 4, that at X fromthe line-wire 3, and that at A from the line-wire 2. In such a systemthere may also be stations connected to separate individual lines andhaving their ringers bridged across the metallic circuit without anyground.

At the central office we show a cord-circuit 7 8 9 10 havingterminalplugs P and P, the former for answering calls and the latter for makingthem. When one of these plugs is inserted in the spring-jack, it forcestogether a pair of contactsjj to short-circuit the linerelay L, wherebythe line-signal may be retired. Each plug is supposed to have associatedwith it a suitable supervisory signal and each cord to have alistening-key with connections to an operators telephone. This we havenot shown, for it forms no part of our invention and would onlycomplicate the drawings. I

The operation of the system thus far described may bebriefly statedasfollows: Suppose subscriber A calls by taking down his receiver.Current from the main battery M sets the line-signal 1 by its relay L.The in sertion of the answering-plug P closes the shunt about theline-relay and restores the signal. Having obtained the number wanted,the operator inserts calling-plug I in jack J (supposing 3 4 to be thewanted line) and by means of the ringing-key K calls up the sub scriberWanted, which may be either B or X, according to the position of themaster-key.

WVhen the subscribers have finished talking, they hang up and theoperator clears out in the ordinary way. This brings us to the means bywhich B or X may be differentiated and the interlocking connectionswherein lies our invention. For the sake of simplicity we will firstdescribe the apparatus in Fig. 2, which shows a cord-circuit that mightwell have been used in the operation described. In this cord-circuit theconductor 7 8 passes through the normally closed contacts 12 13 of theringing-key K and the conductor 9 10 passes throughthe similar normallyclosed contact 14 15. The contacts 12 and 15 are in the shape of springshaving a bend toward each other and adapted to beseparated by theplunger of the key when depressed. On the outside of these springs lie apair of contacts 11 and 16, connected, respectively, by wires 35 and 34to the outer spring-contacts 23 and 24 of the master-key K. Mechanicallyconnected to the spring 15, but electrically insulated therefrom, is aspring 17, normally apart from but adapted to be forced by the motion ofspring 15 into contact with a contact 18. These springs 17 and 18 arethe terminals of a circuit 28 27, including a battery M (usually themain battery) and the locking-magnet N. It will be understood that thesprings 11 12 13 14 15 16 17 18 are supported in practice upon a blockof insulation such as that shown at 71; for the master-key in bothfigures.

The master-key K comprises a pivoted hub 7r, carrying a handle k and ablock of insulation and having a long arm 70 and a short arm 70*extending out on either side. The former is the locking-arm and thelatter serves for the attachment of a suitable retractile spring whichnormally draws it down and throws the block of insulation 7t" to theleft, as shown. In a notch formed in the lower face of the block 71:rests the upper end of a spring 21, supported at its lower end, as arealso the springs 23 and 24, by insulation F, and this spring 21 isconnected by wire 30 to the ringing-generator G, which on the other sideis to ground by wire 32. It will be observed that if the handle 70 isleft in the position shown the circuit of this generator is completefrom the ground by way of wires 32 and 30, springs 21 and 24, and Wire34 to contact 16 of the ringing-key, and when the plunger of the latteris depressed this circuit will be continued by contact between 16 and 15through conductor 10 to the sleeve of the plugP, and if that plug is ina jack J through the sleeve of the jack to wire 3, and thence to groundthrough ringerQat station X. This is the normal path of current when themaster-key is not disturbed, it being held in the position shown by itsspring and returned to that position by the spring when moved. Thus whenit is desired to call any station whose ringer is connected on thesleeve side of line the operator need manipulate the ringing-key K only.The advantage of this arrangement will appear after a momentsconsideration. change that it is desired to have every line uniform atthe outset, but capable of having additional stations connected whenrequired. In such case all the station ringers are put to ground fromthe sleeve side of line, and to call hold the same down. -w1ll remainlocked as long as the key K is any of them requires only the ringing-keyK. Suppose now in the course of events that ten per cent. of the linescarry two parties each. At first glance it would appear that theoperator must punch a selective key for ten per cent. of her calls, andin the ordinary system this would be so; but in the present case it isnot, for one-half of the parties on these lines being connected on thesleeve side are called uniformly with the rest of the exchange. Henceselection will have to be made in only five per cent, supposing thecall-load to be uniformly distributed,which itis not. By taking thoseparties who receive the fewest calls and always putting them on the tipside, putting the busiest phones on the sleeve side, a manager mayreduce the percentage to anything from one per cent. up.

If it is desired to call station B, still using the cord-circuit of Fig.2, the operator throws over the handle to the left, whereby the spring21 is moved to the right, breaking contact with spring 24 and making itwith spring 23. The generator is thus shifted onto the mainspring 11 ofthe ringing keylK, the actuation of which connects the generator throughconductor 8 with the tip of plug P, and if that is in a jack thence toline-wire 4 and through the ringer at station B to ground.

Whenever the plunger of key K is depressed, the contacts 17 18 are puttogether and the circuit 27 28 is closed, energizing the magnet M. Thispulls down its armature a, which forms part of a bell-crank lever N,pivoted at a and carrying at its upper end a projecting detent-fingerof. This finger engages with the arm 70 when the armature n isattracted, but is normally drawn back away from the arm by a suitableretractile spring. Thus when the lever F has been shifted over and theringing-key K has been depressed the bell-crank N swings about itspivot, 'so that the finger n engages over the arm k to Obviously the keyK down, and while this is a convenienceto the operator,'in that it savesher from having to hold the master-key, it is also a safeguard, for ifshe attempts to make a second selection too rapidly before theringingkey on the first call is released she finds herself locked out,being restricted to one call at a time. It might be objected that withthe master-key looked a false call might be unwittingly sentover the tipside of another line when intended for the normal sleeve side. This isreally not a valid objection, however, for as there is only onemaster-key it can Suppose in an ex be made quite conspicuous, so that ifit, remains in an abnormal position it serves as an almost infalliblereminder to the operator of the condition of some one of her numerousringing-keys. In this connection it may be stated that the springs 23and 24 of the master-key are connected to the springs 11 and 16 of allthe ringing-keys in parallel, as indicated by the short ends of linesattached to the springs.

If, as will mostly be the case, a call is sent with the master-key inthe position shown in the drawings, the finger n will be pulled over assoon as key K is used, hooking under the arm k and keeping the same upuntil the ringing-key is restored. This prevents the throwing over ofthe master-key during normal ringing. If the master-key is thrown overfor a call on the tip side, however, it will be obvious that not onlywill the operator not have to hold it over while sherings, but as soonas she restores the ringing-key to normal the master-key will springback automatically to its own normal position, being released by theretraction of'armature a due to the breaking-of local circuit 27 28.

Referring now to Fig. 1 entirely, we have shown in that figure acord-circuit and ringing-circuits adapted for use with metallic circuitswith ringers bridged, as well as those having the ringers to ground. Itmight well happen that in some cases or in most cases in an exchange thesingle-line subscribcrs that is, those having but one instrument on aline-- should have no grounds and their ringers should be bridged. Inthis case the plugs, cords, and ringing-key K are precisely the same asin Fig. 2. The generator, however, has two wires 30 and 31, connectingit to contacts 21 and 25 and 22 and 26 of the master-key K. The springs19 and 20 and 23 and 24, corresponding to springs 23 and 24 of the otherarrangement, are connected in pairs and to the springs 11 and 16 of theringing-key K. The master-key has a look, as before, consisting of thesame kind of a bell-crank controlled by magnet N in circuit withcontacts 17 and 18 on the ringing-key. The master-key is locked inposition whether up or down as long as the ringing-key is down. Thegenerator G is grounded on one side by the wire 32. With thisarrangement suppose ringing current is to bethrown on the metalliccircuit it follows this path: G, 31, 25, 23, 4:2, 35, 11, 12,cord-conductor 8, sleeve of plug P, out to line and back by the tipside, tip of plug P, cord -conductor 10, 15, 16, 34, 4:3, 21, 30, andback to generator. Observe that this puts the side 30 of thegenerator-circuit to the tip side of line. If the master-key be thrownover to the right. and ringing-key depressed, the connection will bereversed and wire 30 will go by way of spring 26, spring 24, wire 35,spring 11, and spring 12 to sleeve of plug, while the return will be totip 10 15 16 43 20 22 31that is, the generator may be caused to ring ineither direction-and if it gives pulsating current its reversal may sendpositive or negative pulsations to one side of line at will, returningin each. case by the other. One side of the generator is grounded at 32,and consequently as the generator connections are reversed to line thisground is on one side or the other. If, then, there are grounded bells,they may be selected by suitably altering the grounded sidethat is, byturning the masterkey one way or the other. Inasmuch as alternatingcurrent is the same either way the direction of ringing for the metalliccircuit is ordinarily of no moment and, as before, the grounded bellsmost used are put on the sleeve side of the lines. Thus the key in itsnormal position (shown) will permit any metallic circuit-bell or anybell on the sleeve side of line to be rung up without moving the lever.To ring tip side bells, however, the lever is thrown over and when overis locked, of course, until the key K is released.

It may be said that if bells are to ground from both sides of line themetallic-circuit connection would cause both to ring. This is not so,however, as the ringing is usually done through a limiting resistance,such as a bank of incandescent lamps, and it is especially 'not so ifthe bells are high-wound, as they usually are.

Having thus described our invention, what we claim, and desire to secureby Letters Patent, is

1. In a telephone system, a subscribers line and bells connected to theopposite limbs thereof to be actuated by current over one or the otherof the limbs, a ringing-key adapted to make connection with the line, aselective master-key and a generator, the master-key connected andarranged to complete the circuit of said generator in direct or reversedrelations with the contacts of the ringing-key, together with means tolock the master-key when set and means actuated by the ringing-key tocontrol said locking means, substantially as described.

2. In a telephone system, a line-circuit, two stations connected to saidline and signal-bells thereat, one connected to one side of the line andground, and the other to the other side of line and ground, asignaling-generator having a grounded terminal, a switch to connect saidgenerator to line, a second switch to connect the generator in direct orreversed relation to the first switch, so as to bring the groundedterminal to one side or the other of line as desired, together withlocking means therefor, and a controlling connection from. said lockingmeans to the first switch, whereby the second switch is locked when thefirst switch is actuated, substantially as described.

4. In a signaling system, a circuit and two or more signal-receivingdevices connected thereto, signal-transmltting apparatus comprising aselector, a signal-transmitter and means operated by the transmitter tolock the selector, substantially as described.

5. In a party-line telephone system, a subscribers line connected to twoor more subscribers stations, selective receiving apparatus at eachstation, a central station also connected to the line, and an operatorssignaling outfit comprising a selective switch, a ringingkey, a suitablesource of current-supply, a lock for the selective switch, anelectromagnet controlling the lock, and a circuit including said magnetand adapted to be opened and closed in the operation of the ringing-key,substantially as described.

6. In a party-line telephone system, two or more subscribers stations, ametallic circuit passing to all the stations and signal-bells thereatconnected from the opposite limbs of the metallic circuit to groundrespectively, a central station and terminals for the circuit therein,operators metallic cord circuits adapted to make connection therewith,and selective ringing apparatus for said cord-circuits comprising ametallic-circuit ringingkey having sets of contacts connected toopposite sides of each cord-circuit, a generator having one terminalgrounded, a master-key connected to said generator and adapted to'connect the ungrounded terminal thereof to one side or the other of theringingkey, whereby the generator may be included between the ground andeither side of a cordcircuit, a lock adapted to hold the master-key ineither position when actuated, an electromagnet controlling said lockand a circuit for said electromagnet including a source of current-andcontacts controlled by the ringingkey, substantially as described.

In witness whereof we have hereunto signed our names in the presence oftwo subscribing witnesses.

JACOB W. LATTIG. CHARLES LANE GOODRUM.

WVitnesses:

M. S. LEWIS, EDWARD E. CLEMENT.

